20... f6g6  21. a7c6 If the knight is captured, then White gains a powerful passed pawn, and the b5-square becomes available for the other knight. But how is it possible to survive playing against such a monster piece $2 21... b8c8  22. g2g3 Keeping some options on the kingside as well. At this point, Caruana was probably considering using the h3-c8 diagonal either for the queen or for the bishop. 22... c8d7 